1
2/*
3 * Code and supporting documentation (c) Copyright 1990 1991 Tektronix, Inc.
4 * 	All Rights Reserved
5 *
6 * This file is a component of an X Window System-specific implementation
7 * of XCMS based on the TekColor Color Management System.  Permission is
8 * hereby granted to use, copy, modify, sell, and otherwise distribute this
9 * software and its documentation for any purpose and without fee, provided
10 * that this copyright, permission, and disclaimer notice is reproduced in
11 * all copies of this software and in supporting documentation.  TekColor
12 * is a trademark of Tektronix, Inc.
13 *
14 * Tektronix makes no representation about the suitability of this software
15 * for any purpose.  It is provided "as is" and with all faults.
16 *
17 * TEKTRONIX DISCLAIMS ALL WARRANTIES APPLICABLE TO THIS SOFTWARE,
18 * INCLUDING THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
19 * PARTICULAR PURPOSE.  IN NO EVENT SHALL TEKTRONIX BE LIABLE FOR ANY
20 * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
21 * RESULTING FROM LOSS OF USE, DATA, OR PROFITS, WHETHER IN AN ACTION OF
22 * CONTRACT, NEGLIGENCE, OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
23 * CONNECTION WITH THE USE OR THE PERFORMANCE OF THIS SOFTWARE.
24 *
25 *	NAME
26 *		CIELabGcLC.c
27 *
28 *	DESCRIPTION
29 *		Source for XcmsCIELabClipLab() gamut
30 *		compression function.
31 */
32
33#ifdef HAVE_CONFIG_H
34#include <config.h>
35#endif
36#include "Xlibint.h"
37#include "Xcmsint.h"
38#include <math.h>
39#include "Cv.h"
40
41/*
42 *	INTERNALS
43 *		Internal defines that need NOT be exported to any package or
44 *		program using this package.
45 */
46#define MAXBISECTCOUNT	100
47
48
49/************************************************************************
50 *									*
51 *			 PUBLIC ROUTINES				*
52 *									*
53 ************************************************************************/
54
55/*
56 *	NAME
57 *		XcmsCIELabClipLab - Return the closest L* and chroma
58 *
59 *	SYNOPSIS
60 */
61/* ARGSUSED */
62Status
63XcmsCIELabClipLab (
64    XcmsCCC ccc,
65    XcmsColor *pColors_in_out,
66    unsigned int nColors,
67    unsigned int i,
68    Bool *pCompressed)
69/*
70 *	DESCRIPTION
71 *		This routine will find the closest L* and chroma
72 *		for a specific hue.  The color input is converted to
73 *		CIE L*u*v* format and returned as CIE XYZ format.
74 *
75 *		Since this routine works with the L* within
76 *		pColor_in_out intermediate results may be returned
77 *		even though it may be invalid.
78 *
79 *	RETURNS
80 *		XcmsFailure - Failure
81 *              XcmsSuccess - Succeeded
82 *
83 */
84{
85    Status retval;
86    XcmsCCCRec	myCCC;
87    XcmsColor	*pColor;
88    XcmsColor	Lab_max;
89    XcmsFloat	hue, chroma, maxChroma;
90    XcmsFloat	Chroma, bestChroma, Lstar, maxLstar, saveLstar;
91    XcmsFloat	bestLstar, bestastar, bestbstar;
92    XcmsFloat	nT, saveDist, tmpDist;
93    XcmsRGBi	rgb_max;
94    int		nCount, nMaxCount, nI, nILast;
95
96    /* Use my own CCC */
97    memcpy ((char *)&myCCC, (char *)ccc, sizeof(XcmsCCCRec));
98    myCCC.clientWhitePt.format = XcmsUndefinedFormat;/* inherit screen white */
99    myCCC.gamutCompProc = (XcmsCompressionProc)NULL;/* no gamut compression func */
100
101    /*
102     * Color specification passed as input can be assumed to:
103     *	1. Be in XcmsCIEXYZFormat
104     *	2. Already be white point adjusted for the Screen White Point.
105     *	    This means that the white point now associated with this
106     *	    color spec is the Screen White Point (even if the
107     *	    ccc->clientWhitePt differs).
108     */
109
110    pColor = pColors_in_out + i;
111
112    if (ccc->visual->class < StaticColor) {
113	/*
114	 * GRAY !
115	 */
116	_XcmsDIConvertColors(ccc, pColor, ScreenWhitePointOfCCC(ccc),
117		1, XcmsCIELabFormat);
118	_XcmsDIConvertColors(ccc, pColor, ScreenWhitePointOfCCC(ccc),
119		1, XcmsCIEXYZFormat);
120	if (pCompressed) {
121	    *(pCompressed + i) = True;
122	}
123	return(XcmsSuccess);
124    }
125
126    /* Convert from CIEXYZ to CIELab format */
127    if (_XcmsDIConvertColors(&myCCC, pColor,
128		            ScreenWhitePointOfCCC(&myCCC), 1, XcmsCIELabFormat)
129		== XcmsFailure) {
130	return(XcmsFailure);
131    }
132
133    /* Step 1: compute the maximum L* and chroma for this hue. */
134    /*         This copy may be overkill but it preserves the pixel etc. */
135    saveLstar = pColor->spec.CIELab.L_star;
136    hue = XCMS_CIELAB_PMETRIC_HUE(pColor->spec.CIELab.a_star,
137				  pColor->spec.CIELab.b_star);
138    chroma = XCMS_CIELAB_PMETRIC_CHROMA(pColor->spec.CIELab.a_star,
139					pColor->spec.CIELab.b_star);
140    memcpy((char *)&Lab_max, (char *)pColor, sizeof(XcmsColor));
141    if (_XcmsCIELabQueryMaxLCRGB (&myCCC, hue, &Lab_max, &rgb_max)
142	    == XcmsFailure) {
143	return (XcmsFailure);
144    }
145    maxLstar = Lab_max.spec.CIELab.L_star;
146
147    /* Now check and return the appropriate L* */
148    if (saveLstar == maxLstar) {
149	/* When the L* input is equal to the maximum L* */
150	/* merely return the maximum Lab point. */
151	memcpy((char *)pColor, (char *)&Lab_max, sizeof(XcmsColor));
152	retval = _XcmsDIConvertColors(&myCCC, pColor,
153		           ScreenWhitePointOfCCC(&myCCC), 1, XcmsCIEXYZFormat);
154    } else {
155	/* return the closest point on the hue leaf. */
156	/* must do a bisection here to compute the delta e. */
157	maxChroma = XCMS_CIELAB_PMETRIC_CHROMA(Lab_max.spec.CIELab.a_star,
158					       Lab_max.spec.CIELab.b_star);
159	nMaxCount = MAXBISECTCOUNT;
160	nI = nMaxCount / 2;
161	bestLstar = Lstar =  pColor->spec.CIELab.L_star;
162	bestastar = pColor->spec.CIELab.a_star;
163	bestbstar = pColor->spec.CIELab.b_star;
164	bestChroma = Chroma = chroma;
165	saveDist = XCMS_SQRT(((Chroma - maxChroma) * (Chroma - maxChroma)) +
166			     ((Lstar - maxLstar) * (Lstar - maxLstar)));
167	for (nCount = 0; nCount < nMaxCount; nCount++) {
168	    nT = (XcmsFloat) nI / (XcmsFloat) nMaxCount;
169	    if (saveLstar > maxLstar) {
170		pColor->spec.RGBi.red   = rgb_max.red * (1.0 - nT) + nT;
171		pColor->spec.RGBi.green = rgb_max.green * (1.0 - nT) + nT;
172		pColor->spec.RGBi.blue  = rgb_max.blue * (1.0 - nT) + nT;
173	    } else {
174		pColor->spec.RGBi.red   = rgb_max.red - (rgb_max.red * nT);
175		pColor->spec.RGBi.green = rgb_max.green - (rgb_max.green * nT);
176		pColor->spec.RGBi.blue  = rgb_max.blue - (rgb_max.blue * nT);
177	    }
178	    pColor->format = XcmsRGBiFormat;
179
180	    /* Convert from RGBi to CIE Lab */
181	    if (_XcmsConvertColorsWithWhitePt(&myCCC, pColor,
182	                    ScreenWhitePointOfCCC(&myCCC), 1, XcmsCIELabFormat,
183			    (Bool *) NULL) == XcmsFailure) {
184		return (XcmsFailure);
185	    }
186	    chroma = XCMS_CIELAB_PMETRIC_CHROMA(pColor->spec.CIELab.a_star,
187					        pColor->spec.CIELab.b_star);
188	    tmpDist = XCMS_SQRT(((Chroma - chroma) * (Chroma - chroma)) +
189			        ((Lstar - pColor->spec.CIELab.L_star) *
190				 (Lstar - pColor->spec.CIELab.L_star)));
191	    nILast = nI;
192	    if (tmpDist > saveDist) {
193		nI /= 2;
194	    } else {
195		nI = (nMaxCount + nI) / 2;
196		saveDist = tmpDist;
197		bestLstar = pColor->spec.CIELab.L_star;
198		bestastar = pColor->spec.CIELab.a_star;
199		bestbstar = pColor->spec.CIELab.b_star;
200		bestChroma = chroma;
201	    }
202	    if (nI == nILast || nI == 0) {
203		break;
204	    }
205	}
206	if (bestChroma >= maxChroma) {
207	    pColor->spec.CIELab.L_star = maxLstar;
208	    pColor->spec.CIELab.a_star = Lab_max.spec.CIELab.a_star;
209	    pColor->spec.CIELab.b_star = Lab_max.spec.CIELab.b_star;
210	} else {
211	    pColor->spec.CIELab.L_star = bestLstar;
212	    pColor->spec.CIELab.a_star = bestastar;
213	    pColor->spec.CIELab.b_star = bestbstar;
214	}
215	retval = _XcmsDIConvertColors(&myCCC, pColor,
216		           ScreenWhitePointOfCCC(&myCCC), 1, XcmsCIEXYZFormat);
217
218	if (retval != XcmsFailure && pCompressed != NULL) {
219	    *(pCompressed + i) = True;
220	}
221    }
222    return(retval);
223}
224